/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package javax.servlet.http;

import java.io.IOException;

import javax.servlet.ServletResponse;

/**
 * 
 * Extends the {@link ServletResponse} interface to provide HTTP-specific
 * functionality in sending a response. For example, it has methods to access
 * HTTP headers and cookies.
 * 
 * <p>
 * The servlet container creates an <code>HttpServletResponse</code> object and
 * passes it as an argument to the servlet's service methods (<code>doGet</code>, <code>doPost</code>, etc).
 * 
 * 
 * @author Various
 * @version $Version$
 * 
 * @see javax.servlet.ServletResponse
 * 
 */

public interface HttpServletResponse extends ServletResponse {

	/**
	 * Adds the specified cookie to the response. This method can be called
	 * multiple times to set more than one cookie.
	 * 
	 * @param cookie
	 *            the Cookie to return to the client
	 * 
	 */

	public void addCookie(Cookie cookie);

	/**
	 * Returns a boolean indicating whether the named response header has
	 * already been set.
	 * 
	 * @param name
	 *            the header name
	 * @return <code>true</code> if the named response header has already been
	 *         set; <code>false</code> otherwise
	 */

	public boolean containsHeader(String name);

	/**
	 * Encodes the specified URL by including the session ID in it, or, if
	 * encoding is not needed, returns the URL unchanged. The implementation of
	 * this method includes the logic to determine whether the session ID needs
	 * to be encoded in the URL. For example, if the browser supports cookies,
	 * or session tracking is turned off, URL encoding is unnecessary.
	 * 
	 * <p>
	 * For robust session tracking, all URLs emitted by a servlet should be run
	 * through this method. Otherwise, URL rewriting cannot be used with
	 * browsers which do not support cookies.
	 * 
	 * @param url
	 *            the url to be encoded.
	 * @return the encoded URL if encoding is needed; the unchanged URL
	 *         otherwise.
	 */

	public String encodeURL(String url);

	/**
	 * Encodes the specified URL for use in the <code>sendRedirect</code> method
	 * or, if encoding is not needed, returns the URL unchanged. The
	 * implementation of this method includes the logic to determine whether the
	 * session ID needs to be encoded in the URL. Because the rules for making
	 * this determination can differ from those used to decide whether to encode
	 * a normal link, this method is separated from the <code>encodeURL</code>
	 * method.
	 * 
	 * <p>
	 * All URLs sent to the <code>HttpServletResponse.sendRedirect</code> method
	 * should be run through this method. Otherwise, URL rewriting cannot be
	 * used with browsers which do not support cookies.
	 * 
	 * @param url
	 *            the url to be encoded.
	 * @return the encoded URL if encoding is needed; the unchanged URL
	 *         otherwise.
	 * 
	 * @see #sendRedirect
	 * @see #encodeUrl
	 */

	public String encodeRedirectURL(String url);

	/**
	 * @deprecated As of version 2.1, use encodeURL(String url) instead
	 * 
	 * @param url
	 *            the url to be encoded.
	 * @return the encoded URL if encoding is needed; the unchanged URL
	 *         otherwise.
	 */

	public String encodeUrl(String url);

	/**
	 * @deprecated As of version 2.1, use encodeRedirectURL(String url) instead
	 * 
	 * @param url
	 *            the url to be encoded.
	 * @return the encoded URL if encoding is needed; the unchanged URL
	 *         otherwise.
	 */

	public String encodeRedirectUrl(String url);

	/**
	 * Sends an error response to the client using the specified status. The
	 * server defaults to creating the response to look like an HTML-formatted
	 * server error page containing the specified message, setting the content
	 * type to "text/html", leaving cookies and other headers unmodified.
	 * 
	 * If an error-page declaration has been made for the web application
	 * corresponding to the status code passed in, it will be served back in
	 * preference to the suggested msg parameter.
	 * 
	 * <p>
	 * If the response has already been committed, this method throws an
	 * IllegalStateException. After using this method, the response should be
	 * considered to be committed and should not be written to.
	 * 
	 * @param sc
	 *            the error status code
	 * @param msg
	 *            the descriptive message
	 * @exception IOException
	 *                If an input or output exception occurs
	 * @exception IllegalStateException
	 *                If the response was committed
	 */

	public void sendError(int sc, String msg) throws IOException;

	/**
	 * Sends an error response to the client using the specified status code and
	 * clearing the buffer.
	 * <p>
	 * If the response has already been committed, this method throws an
	 * IllegalStateException. After using this method, the response should be
	 * considered to be committed and should not be written to.
	 * 
	 * @param sc
	 *            the error status code
	 * @exception IOException
	 *                If an input or output exception occurs
	 * @exception IllegalStateException
	 *                If the response was committed before this method call
	 */

	public void sendError(int sc) throws IOException;

	/**
	 * Sends a temporary redirect response to the client using the specified
	 * redirect location URL. This method can accept relative URLs; the servlet
	 * container must convert the relative URL to an absolute URL before sending
	 * the response to the client. If the location is relative without a leading
	 * '/' the container interprets it as relative to the current request URI.
	 * If the location is relative with a leading '/' the container interprets
	 * it as relative to the servlet container root.
	 * 
	 * <p>
	 * If the response has already been committed, this method throws an
	 * IllegalStateException. After using this method, the response should be
	 * considered to be committed and should not be written to.
	 * 
	 * @param location
	 *            the redirect location URL
	 * @exception IOException
	 *                If an input or output exception occurs
	 * @exception IllegalStateException
	 *                If the response was committed or if a partial URL is given
	 *                and cannot be converted into a valid URL
	 */

	public void sendRedirect(String location) throws IOException;

	/**
	 * 
	 * Sets a response header with the given name and date-value. The date is
	 * specified in terms of milliseconds since the epoch. If the header had
	 * already been set, the new value overwrites the previous one. The
	 * <code>containsHeader</code> method can be used to test for the presence
	 * of a header before setting its value.
	 * 
	 * @param name
	 *            the name of the header to set
	 * @param date
	 *            the assigned date value
	 * 
	 * @see #containsHeader
	 * @see #addDateHeader
	 */

	public void setDateHeader(String name, long date);

	/**
	 * 
	 * Adds a response header with the given name and date-value. The date is
	 * specified in terms of milliseconds since the epoch. This method allows
	 * response headers to have multiple values.
	 * 
	 * @param name
	 *            the name of the header to set
	 * @param date
	 *            the additional date value
	 * 
	 * @see #setDateHeader
	 */

	public void addDateHeader(String name, long date);

	/**
	 * 
	 * Sets a response header with the given name and value. If the header had
	 * already been set, the new value overwrites the previous one. The
	 * <code>containsHeader</code> method can be used to test for the presence
	 * of a header before setting its value.
	 * 
	 * @param name
	 *            the name of the header
	 * @param value
	 *            the header value If it contains octet string, it should be
	 *            encoded according to RFC 2047
	 *            (http://www.ietf.org/rfc/rfc2047.txt)
	 * 
	 * @see #containsHeader
	 * @see #addHeader
	 */

	public void setHeader(String name, String value);

	/**
	 * Adds a response header with the given name and value. This method allows
	 * response headers to have multiple values.
	 * 
	 * @param name
	 *            the name of the header
	 * @param value
	 *            the additional header value If it contains octet string, it
	 *            should be encoded according to RFC 2047
	 *            (http://www.ietf.org/rfc/rfc2047.txt)
	 * 
	 * @see #setHeader
	 */

	public void addHeader(String name, String value);

	/**
	 * Sets a response header with the given name and integer value. If the
	 * header had already been set, the new value overwrites the previous one.
	 * The <code>containsHeader</code> method can be used to test for the
	 * presence of a header before setting its value.
	 * 
	 * @param name
	 *            the name of the header
	 * @param value
	 *            the assigned integer value
	 * 
	 * @see #containsHeader
	 * @see #addIntHeader
	 */

	public void setIntHeader(String name, int value);

	/**
	 * Adds a response header with the given name and integer value. This method
	 * allows response headers to have multiple values.
	 * 
	 * @param name
	 *            the name of the header
	 * @param value
	 *            the assigned integer value
	 * 
	 * @see #setIntHeader
	 */

	public void addIntHeader(String name, int value);

	/**
	 * Sets the status code for this response. This method is used to set the
	 * return status code when there is no error (for example, for the status
	 * codes SC_OK or SC_MOVED_TEMPORARILY). If there is an error, and the
	 * caller wishes to invoke an error-page defined in the web application, the
	 * <code>sendError</code> method should be used instead.
	 * <p>
	 * The container clears the buffer and sets the Location header, preserving
	 * cookies and other headers.
	 * 
	 * @param sc
	 *            the status code
	 * 
	 * @see #sendError
	 */

	public void setStatus(int sc);

	/**
	 * @deprecated As of version 2.1, due to ambiguous meaning of the message
	 *             parameter. To set a status code use
	 *             <code>setStatus(int)</code>, to send an error with a
	 *             description use <code>sendError(int, String)</code>.
	 * 
	 *             Sets the status code and message for this response.
	 * 
	 * @param sc
	 *            the status code
	 * @param sm
	 *            the status message
	 */

	public void setStatus(int sc, String sm);

	/*
	 * Server status codes; see RFC 2068.
	 */

	/**
	 * Status code (100) indicating the client can continue.
	 */

	public static final int SC_CONTINUE = 100;

	/**
	 * Status code (101) indicating the server is switching protocols according
	 * to Upgrade header.
	 */

	public static final int SC_SWITCHING_PROTOCOLS = 101;

	/**
	 * Status code (200) indicating the request succeeded normally.
	 */

	public static final int SC_OK = 200;

	/**
	 * Status code (201) indicating the request succeeded and created a new
	 * resource on the server.
	 */

	public static final int SC_CREATED = 201;

	/**
	 * Status code (202) indicating that a request was accepted for processing,
	 * but was not completed.
	 */

	public static final int SC_ACCEPTED = 202;

	/**
	 * Status code (203) indicating that the meta information presented by the
	 * client did not originate from the server.
	 */

	public static final int SC_NON_AUTHORITATIVE_INFORMATION = 203;

	/**
	 * Status code (204) indicating that the request succeeded but that there
	 * was no new information to return.
	 */

	public static final int SC_NO_CONTENT = 204;

	/**
	 * Status code (205) indicating that the agent <em>SHOULD</em> reset the
	 * document view which caused the request to be sent.
	 */

	public static final int SC_RESET_CONTENT = 205;

	/**
	 * Status code (206) indicating that the server has fulfilled the partial
	 * GET request for the resource.
	 */

	public static final int SC_PARTIAL_CONTENT = 206;

	/**
	 * Status code (300) indicating that the requested resource corresponds to
	 * any one of a set of representations, each with its own specific location.
	 */

	public static final int SC_MULTIPLE_CHOICES = 300;

	/**
	 * Status code (301) indicating that the resource has permanently moved to a
	 * new location, and that future references should use a new URI with their
	 * requests.
	 */

	public static final int SC_MOVED_PERMANENTLY = 301;

	/**
	 * Status code (302) indicating that the resource has temporarily moved to
	 * another location, but that future references should still use the
	 * original URI to access the resource.
	 * 
	 * This definition is being retained for backwards compatibility. SC_FOUND
	 * is now the preferred definition.
	 */

	public static final int SC_MOVED_TEMPORARILY = 302;

	/**
	 * Status code (302) indicating that the resource reside temporarily under a
	 * different URI. Since the redirection might be altered on occasion, the
	 * client should continue to use the Request-URI for future
	 * requests.(HTTP/1.1) To represent the status code (302), it is recommended
	 * to use this variable.
	 */

	public static final int SC_FOUND = 302;

	/**
	 * Status code (303) indicating that the response to the request can be
	 * found under a different URI.
	 */

	public static final int SC_SEE_OTHER = 303;

	/**
	 * Status code (304) indicating that a conditional GET operation found that
	 * the resource was available and not modified.
	 */

	public static final int SC_NOT_MODIFIED = 304;

	/**
	 * Status code (305) indicating that the requested resource <em>MUST</em> be
	 * accessed through the proxy given by the <code><em>Location</em></code>
	 * field.
	 */

	public static final int SC_USE_PROXY = 305;

	/**
	 * Status code (307) indicating that the requested resource resides
	 * temporarily under a different URI. The temporary URI <em>SHOULD</em> be
	 * given by the <code><em>Location</em></code> field in the response.
	 */

	public static final int SC_TEMPORARY_REDIRECT = 307;

	/**
	 * Status code (400) indicating the request sent by the client was
	 * syntactically incorrect.
	 */

	public static final int SC_BAD_REQUEST = 400;

	/**
	 * Status code (401) indicating that the request requires HTTP
	 * authentication.
	 */

	public static final int SC_UNAUTHORIZED = 401;

	/**
	 * Status code (402) reserved for future use.
	 */

	public static final int SC_PAYMENT_REQUIRED = 402;

	/**
	 * Status code (403) indicating the server understood the request but
	 * refused to fulfill it.
	 */

	public static final int SC_FORBIDDEN = 403;

	/**
	 * Status code (404) indicating that the requested resource is not
	 * available.
	 */

	public static final int SC_NOT_FOUND = 404;

	/**
	 * Status code (405) indicating that the method specified in the
	 * <code><em>Request-Line</em></code> is not allowed for the resource
	 * identified by the <code><em>Request-URI</em></code>.
	 */

	public static final int SC_METHOD_NOT_ALLOWED = 405;

	/**
	 * Status code (406) indicating that the resource identified by the request
	 * is only capable of generating response entities which have content
	 * characteristics not acceptable according to the accept headers sent in
	 * the request.
	 */

	public static final int SC_NOT_ACCEPTABLE = 406;

	/**
	 * Status code (407) indicating that the client <em>MUST</em> first
	 * authenticate itself with the proxy.
	 */

	public static final int SC_PROXY_AUTHENTICATION_REQUIRED = 407;

	/**
	 * Status code (408) indicating that the client did not produce a request
	 * within the time that the server was prepared to wait.
	 */

	public static final int SC_REQUEST_TIMEOUT = 408;

	/**
	 * Status code (409) indicating that the request could not be completed due
	 * to a conflict with the current state of the resource.
	 */

	public static final int SC_CONFLICT = 409;

	/**
	 * Status code (410) indicating that the resource is no longer available at
	 * the server and no forwarding address is known. This condition
	 * <em>SHOULD</em> be considered permanent.
	 */

	public static final int SC_GONE = 410;

	/**
	 * Status code (411) indicating that the request cannot be handled without a
	 * defined <code><em>Content-Length</em></code>.
	 */

	public static final int SC_LENGTH_REQUIRED = 411;

	/**
	 * Status code (412) indicating that the precondition given in one or more
	 * of the request-header fields evaluated to false when it was tested on the
	 * server.
	 */

	public static final int SC_PRECONDITION_FAILED = 412;

	/**
	 * Status code (413) indicating that the server is refusing to process the
	 * request because the request entity is larger than the server is willing
	 * or able to process.
	 */

	public static final int SC_REQUEST_ENTITY_TOO_LARGE = 413;

	/**
	 * Status code (414) indicating that the server is refusing to service the
	 * request because the <code><em>Request-URI</em></code> is longer than the
	 * server is willing to interpret.
	 */

	public static final int SC_REQUEST_URI_TOO_LONG = 414;

	/**
	 * Status code (415) indicating that the server is refusing to service the
	 * request because the entity of the request is in a format not supported by
	 * the requested resource for the requested method.
	 */

	public static final int SC_UNSUPPORTED_MEDIA_TYPE = 415;

	/**
	 * Status code (416) indicating that the server cannot serve the requested
	 * byte range.
	 */

	public static final int SC_REQUESTED_RANGE_NOT_SATISFIABLE = 416;

	/**
	 * Status code (417) indicating that the server could not meet the
	 * expectation given in the Expect request header.
	 */

	public static final int SC_EXPECTATION_FAILED = 417;

	/**
	 * Status code (500) indicating an error inside the HTTP server which
	 * prevented it from fulfilling the request.
	 */

	public static final int SC_INTERNAL_SERVER_ERROR = 500;

	/**
	 * Status code (501) indicating the HTTP server does not support the
	 * functionality needed to fulfill the request.
	 */

	public static final int SC_NOT_IMPLEMENTED = 501;

	/**
	 * Status code (502) indicating that the HTTP server received an invalid
	 * response from a server it consulted when acting as a proxy or gateway.
	 */

	public static final int SC_BAD_GATEWAY = 502;

	/**
	 * Status code (503) indicating that the HTTP server is temporarily
	 * overloaded, and unable to handle the request.
	 */

	public static final int SC_SERVICE_UNAVAILABLE = 503;

	/**
	 * Status code (504) indicating that the server did not receive a timely
	 * response from the upstream server while acting as a gateway or proxy.
	 */

	public static final int SC_GATEWAY_TIMEOUT = 504;

	/**
	 * Status code (505) indicating that the server does not support or refuses
	 * to support the HTTP protocol version that was used in the request
	 * message.
	 */

	public static final int SC_HTTP_VERSION_NOT_SUPPORTED = 505;
}
